The present invention relates to a human image retrieval system and more particularly to information retrieval running on a computer.
In addition to programs broadcast/created by broadcasting stations and video creating companies, various video contents including moving images created/recorded by individuals are presented to users via the Internet in recent years, and viewable contents are increasing day after day. As video recording apparatus have high capacity and become low in price, an amount of recordable contents is increasing correspondingly.
Recent years, various techniques have been proposed for detecting and presenting a scene in which a particular person can be viewed, from a huge amount of video contents. These techniques are applied to a video retrieval system for retrieving a drama or a commercial played by a favorite actor from recorded TV images and to an image monitoring system for searching a particular person from images recorded by using a monitor camera installed in an air port or a station yard.
Data desired by a user using such a system is often presented through an approach to similarity retrieval or grouping.
Similarity retrieval is a technique for searching data similar to a retrieval query designated by a user from video contents and presenting the retrieval results. Similarity based image retrieval in particular is a technique for retrieving data having a high degree of similarity by using image features such as color and shape derived from an image itself. For example, when a person is to be retrieved, a face image, a clothes color and the like can be used as the retrieval query.
JP-A-2005-352727 proposes a face image retrieval system for retrieving image data photographing a desired person by paying attention to particular parts such as eyes and a mouth in a face image, extracting image features of these parts, and evaluating a degree of similarity of each part in each face image held in a retrieval object image group.
Grouping is a technique for forming an image group by collecting similar face images and scenes in video contents and presenting a user with only a representative image in the image group to allow the user to easily select a desired face image or scene.
JP-A-2001-167110 proposes an image retrieval method and system for forming a group of faces of the same person by calculating a degree of similarity between all face images detected from video contents and regarding each face image whose degree of similarity exceeds a threshold value, as the same person, extracting a representative face image of each image character, and displaying each image character in the video contents in a distinguishable manner.
JP-A-2003-009069 proposes a moving image reproducing method and system for presenting a user intending to select a desired scene in video contents with a representative image of each of a plurality of scenes divided from the video contents. In forming a representative image of each scene, a delimiter of the scene is detected to form a still image delimited by detected division points. Thereafter, a degree of similarity between a representative image of one scene and a representative image of the next scene is calculated, and if it is judged that the representative images are similar because the degree of similarity of each image exceeds a predetermined threshold value, these images having a high degree of similarity are grouped to present only representative images having a low degree of similarity as selection candidates.